Luts Heleen, Maj Jean-Baptiste, Soede Wim, Wouters Jan
Laboratory for Experimental Otorhinolaryngology, Faculty of Medicine, Katholieke Universiteit Leuven, Kapucijnenvoer 33, B-3000 Leuven, Belgium.
Ear Hear. 2004 Oct;25(5):411-20. doi: 10.1097/01.aud.0000145109.90767.ba.
To evaluate the improvement in speech intelligibility in noise obtained with an assistive real-time fixed endfire array of bidirectional microphones in comparison with an omnidirectional hearing aid microphone in a realistic environment.
The microphone array was evaluated physically in anechoic and reverberant conditions. Perceptual tests of speech intelligibility in noise were carried out in a reverberant room, with two types of noise and six different noise scenarios with single and multiple noise sources. Ten normal-hearing subjects and 10 hearing aid users participated. The speech reception threshold for sentences was measured in each test setting for the omnidirectional microphone of the hearing aid and for the hearing aid in combination with the array with one and three active microphones. In addition, the extra improvement of five active array microphones, relative to three, was determined in another group of 10 normal-hearing listeners.
Improvements in speech intelligibility in noise obtained with the array relative to an omnidirectional microphone depend on noise scenario and subject group. Improvements up to 12 dB for normal-hearing and 9 dB for hearing-impaired listeners were obtained with three active array microphones relative to an omnidirectional microphone for one noise source at 90 degrees . For three uncorrelated noise sources at 90 degrees, 180 degrees, and 270 degrees, improvements of approximately 9 dB and 6 dB were obtained for normal-hearing and hearing-impaired listeners, respectively. Even with a single noise source at 45 degrees, benefits of 4 dB were achieved in both subject groups. Five active microphones in the array can provide an additional improvement at 45 degrees of approximately 1 dB, relative to the three-microphone configuration for normal-hearing listeners.
These improvements in signal-to-noise ratio can be of great benefit for hearing aid users, who have difficulties with speech understanding in noisy environments.
在现实环境中，评估与全向性助听器麦克风相比，辅助实时固定端射双向麦克风阵列在噪声环境下对言语清晰度的改善情况。
在消声和混响条件下对麦克风阵列进行物理评估。在混响室中进行噪声环境下言语清晰度的感知测试，采用两种类型的噪声以及六种不同的单噪声源和多噪声源噪声场景。10名听力正常的受试者和10名助听器使用者参与测试。在每个测试设置中，测量助听器全向性麦克风以及与配备一个和三个有源麦克风的阵列组合使用时助听器的句子言语接受阈。此外，在另一组10名听力正常的听众中，确定五个有源阵列麦克风相对于三个麦克风的额外改善情况。
与全向性麦克风相比，阵列在噪声环境下对言语清晰度的改善取决于噪声场景和受试者群体。对于90度的一个噪声源，相对于全向性麦克风，配备三个有源阵列麦克风时，听力正常的受试者言语清晰度改善高达12分贝，听力受损的受试者改善高达9分贝。对于90度、180度和270度的三个不相关噪声源，听力正常的受试者和听力受损的受试者分别改善约9分贝和6分贝。即使在45度有单个噪声源时，两个受试者群体也都实现了4分贝的益处。对于听力正常的听众，阵列中的五个有源麦克风相对于三个麦克风的配置，在45度时可额外提供约1分贝的改善。
这些信噪比的改善对于在嘈杂环境中言语理解有困难的助听器使用者可能大有裨益。
